Building a Timer with several functions

Hi,

I have a client that needs a timer.

I have found some good tutorials and seen some good examples. But I need some special functions built into the time.

The most imortant funtion would be a warning at a specified time. example, at the :30 mark a warning would flash and make a sound.

Also, the clock needs a start button.

any ideas would be great.

thanks,

Ponyack